Cost optimization of biogas based power production:comprehensive thermoeconomic analysis and evaluation methods

In this thesis, the comprehensive thermoeconomic analysis and optimization approaches were applied to an existing biogas fuelled and internal combustion engine powered cogeneration system located in Gaziantep with an electrical power output of 1000 kW and a hot water mass flowrate of 20.9 kg/s.In the first part of the thesis, fuel and product cost analyzes of each component in the cogeneration system were carried out with four different thermoeconomic methods: Exergetic cost theory (ECT), modified productive structure analysis (MOPSA), wonergy and specific exergy costing method (SPECO). These methods are based on the developed thermoeconomic principles depending on the exergy. In actual operating conditions, the cost of electricity produced in the cogeneration system was calculated, according to the methods, respectively as $110.06/h (ECT), $85.54/h (MOPSA), $72.50/h (Wonergy) and $141.0/h (SPECO). It is concluded that ECT provides the most rational cost picture as the most detailed method in the context of mathematical analysis based on exergy. In the second part of the thesis, the biogas engine powered cogeneration system was examined using two different thermoeconomic optimization methods: Thermoeconomic functional analysis (TFA) and engineering functional analysis (EFA). Both methods take into consideration only the units in the exhaust gas line as of the functional structures in which they are developed. As a result of the analyses, the optimized thermoeconomic cost of electricity was calculated as $26.86/GJ with the TFA method and $24.40/GJ with the EFA method.